1. Field of the Invention
This invention relates to a paper ejection unit in a print apparatus which includes the paper ejection unit and a image formation unit.
2. Background Art
Hitherto, when a predetermined table height detector provided in a paper ejection unit in a print apparatus detects a paper stack table moved down with an increase in the stack amount of printed paper, the paper ejection unit has been determined full of paper, the paper stack operation of the paper ejection unit has been stopped, and a message indicating that the paper ejection unit is full of paper has been displayed on an operation section of the image formation apparatus.
For example, in an image formation apparatus using electrophotography, such as a copier or a laser beam printer, a paper ejection unit for stacking paper ejected from the image formation apparatus needs to be compatible with various paper sizes and stack a large amount of paper with the widespread use of a high-speed image formation apparatus compatible with various paper sizes. The sizes of paper most frequently used with the image formation apparatus are short sizes of A4, B5, letter, etc. If 2,000 or more sheets of paper of large sizes of B4, A3, leisure, etc., are stacked in an image formation apparatus having a paper ejection unit capable of stacking 2,000 or more sheets of paper of the short sizes (75 g/m2), the total weight containing a printed paper taking-out cage exceeds 20 kg and thus a problem occurs in handling of the operator.
In JP-B-7-115794, the paper-full stack amount is changed based on paper size information.
In related art, the paper top face is detected for detecting the paper stack amount. However, if print is stopped midway or the apparatus is powered down at the time, a problem remains in paper stack amount detection at the restart time if the paper top face is detected for detecting the paper stack amount.
It is an object of the invention to solve the above-described problems. Attention is focused on the fact that the weight of paper that can be handled safely is determined by the paper stack height for each paper size, and it is made possible to change the paper stackable amount for each paper size by a paper stack table moved down gradually with an increase in the stack amount of printed paper and a paper stack table height detector for detecting the position of the paper stack table.